Got the Got the Rebore done and cylinder head opened out ,also the spark plug hole machined so the sparks where it's meant to be. It will pull 4th now but still not right. Fannying about with jetex carbs now. Also stator plate readings were wrong so a new one ordered .Not at the should have bought ...

^... ideal. One thing to watch out for is the compression ratio that you end up running (aim for approx. 8:1 geometric, with squish volume considered), regardless of whether you have your 150 head reprofiled or buy a 175 head already done (some off the 175 heads are too high, others too low). Also,...

FYI - Your easiest ways of resolving this so that it works as it should, in whichever order may suit your pocket best (depending on what is available), are: a) Fit a different gearbox with lower ratio. There are lots of gearboxes that give 5.7 in 4th with the original 15/46 sprockets and 80 link ch...